The present invention is concerned with carbapenem antibiotics having an external or internal quaternary mono- or bicyclic heteroarylalkylthiomethyl group in the 2-position.
Thienamycin is a known carbapenem, broad spectrum antibiotic of the formula: ##STR4## Other derivatives of A are also known.
The present externally or internally alkylated mono- or bicycli 2-quaternary heteroarylalkylthiomethyl substituted carbapenems are believed to have an antibiotic spectrum comparable to A.